SSL 9k power questions

[Enchilada]

Hey gyus,

I'm building an SSL 9K as my first pre and I have a couple of quick questions:

1. The PSU BOM specifies a 20-0-20 trafo, would an 18-0-18 be OK as these are much easier for me to source.

2. If an 18-0-18 is OK, would a 50VA trafo be good for powering 8 preamps or would 4 be safer?

3. Is there any way at all that the SSL 9K could be powered by a wall wart?

Thanks,

Kris

 

[abechap024]

1) Yes, probably just fine

2) 4 would be safer

3) Yes. but not as optimal.

 

[Enchilada]

On Q3, are there any tutorials to achieve this? I'm wanting to build a small RNP style preamp.

Thanks,

Kris

 

[Harpo]

more unlikely that you can source a 36-40VAC center tapped secondary or a 18-20VAC dual secondary wall wart.

 

[abechap024]

more unlikely that you can source a 36-40VAC center tapped secondary or a 18-20VAC dual secondary wall wart.

You don't always need a center-tapped transformer for a dual power supply.

24V ac will easily supply a +/- 18v rails...you might want to up the smoothing caps though

 

[Harpo]

You don't always need a center-tapped transformer for a dual power supply.

24V ac will easily supply a +/- 18v rails...you might want to up the smoothing caps though

sure, but wild guessing with current needed for powering his 8 preamps (and probably phantom by another voltage doubler and/or status-LEDs), a wallwart with required rating will not be easily available as well.

 

[gemini86]

the biggest wall warts I've seen are only 15VA... They'll get much too big at larger wattage, but you could still get an external psu, or ac/dc adapter. Won't be a wall-wart. JLM sells a high quality 48v switcher at 60w that would give your +-24v, then regulate down from there. Not sure how you would get 48v phantom from that setup without a charge pump or dc-dc convertor.

 

[Enchilada]

You don't always need a center-tapped transformer for a dual power supply.

24V ac will easily supply a +/- 18v rails...you might want to up the smoothing caps though

sure, but wild guessing with current needed for powering his 8 preamps (and probably phantom by another voltage doubler and/or status-LEDs), a wallwart with required rating will not be easily available as well.

Sorry, I' didn't make myself clear. I was wanting to know if a single channel SSL 9K could be run from a wall wart, similar to the FMR RNP design.

Thanks gyus  ;D

 

[Enchilada]

Nobody?

 

[Harpo]

Sorry, I' didn't make myself clear.

You still don't.

I was wanting to know if a single channel SSL 9K could be run from a wall wart, similar to the FMR RNP design.

googeling the FMR RNP, this unit comes with 2 channels, additional Hi-Z in, ramped (bug or feature) +48V phantom, level and status indicators, electronically (crosscoupled) balancing driver, microprocessor controlled switching/muting,... , powered by a 9-12V >=1.5A AC or DC wallwart for its internal (probably at least 4 rail) switching supply.
You might want some of these prementioned or other features, all more or less powerhungry, by implementing additional circuits for your SSL 9K as well.
'could be run from a wall wart', sure/maybe/no. Vague answer for vague question. Get a switching supply at whatever needed voltage and current rating, feed it from your wall wart that has to meet the switchers requirements and hope for the best. Building a linear supply for the needed supply rails might be easier to source and be cheaper.

 

[Enchilada]

Sorry, I' didn't make myself clear.

You still don't.

I was wanting to know if a single channel SSL 9K could be run from a wall wart, similar to the FMR RNP design.

googeling the FMR RNP, this unit comes with 2 channels, additional Hi-Z in, ramped (bug or feature) +48V phantom, level and status indicators, electronically (crosscoupled) balancing driver, microprocessor controlled switching/muting,... , powered by a 9-12V >=1.5A AC or DC wallwart for its internal (probably at least 4 rail) switching supply.
You might want some of these prementioned or other features, all more or less powerhungry, by implementing additional circuits for your SSL 9K as well.
'could be run from a wall wart', sure/maybe/no. Vague answer for vague question. Get a switching supply at whatever needed voltage and current rating, feed it from your wall wart that has to meet the switchers requirements and hope for the best. Building a linear supply for the needed supply rails might be easier to source and be cheaper.

My bad again, when I say similar in design to the RNP, I only mean small enclosure + wall wart. I'm not after any of the other design features of the RNP, I just like the simplicity of a small enclosure and a wall wart.

To be honest I was tossing up between the SSL 9K and Peter's Green Pre, would it be easier to run a Green Pre from a wall wart as it runs on 15V. Electrical engineering isn't my strong point so I would follow the V14 design with HPF, phase switch, LEDs and +48V. Would there be any necessary modifications to the PSU linked below or could I just run the AC wire of the wall wart to both AC connectors and the GND to the GND connector?

Thanks again, sorry I'm such a noob!

http://www.twin-x.com/groupdiy/displayimage.php?album=random&cat=10096&pos=-1394

 

[Harpo]

My bad again, when I say similar in design to the RNP, I only mean small enclosure + wall wart. I'm not after any of the other design features of the RNP, I just like the simplicity of a small enclosure and a wall wart.

To be honest I was tossing up between the SSL 9K and Peter's Green Pre, would it be easier to run a Green Pre from a wall wart as it runs on 15V. Electrical engineering isn't my strong point so I would follow the V14 design with HPF, phase switch, LEDs and +48V. Would there be any necessary modifications to the PSU linked below or could I just run the AC wire of the wall wart to both AC connectors and the GND to the GND connector?

Thanks again, sorry I'm such a noob!

http://www.twin-x.com/groupdiy/displayimage.php?album=random&cat=10096&pos=-1394

Both SSL 9K and the Green pre want a dual rail (+V, 0V and -V) supply. "as it runs on 15V" is, both Green and 9K can run on +15V and -15V with 0V in between, thats a differential of 30V. Phantom +48V is a 3rd supply rail, if so required.
For connecting the linked PSU to your 15V or 18V secondary AC wall wart, you'd take one wall wart secondary wire to the upper PSUs AC in soldering hole and the corresponding other wall wart secondary wire to the PSUs GND in soldering hole. Leave the center PSUs AC in soldering hole disconnected. For +48V phantom you fit parts (diodes and caps) for a voltage tripler config.

 

[Enchilada]

So this can only be done with two wall warts? I wonder how FMR made it happen?

 

[Harpo]

:

 

[gemini86]

... powered by a 9-12V >=1.5A AC or DC wallwart for its internal (probably at least 4 rail) switching supply.

...could be run from a wall wart', sure/maybe/no. Vague answer for vague question. Get a switching supply at whatever needed voltage and current rating, feed it from your wall wart that has to meet the switchers requirements and hope for the best. Building a linear supply for the needed supply rails might be easier to source and be cheaper.

He just said it. Their walwart is just supplying one power option, then internally it's splitting it up with switching supplies into the required +,- and p48 voltages... It's all micro-sized SMPS magic that makes it happen, not a couple diodes and caps like you might think.

Like I said before, you could power is from, say a 30VDC walwart, then inside the box split it up into +- 15v (using zeners) for your rails. There's still the issue of 48v. I'm going to promise you that your easiest solution will be to just built a 9K PSU into a small external enclosure, use some 4 conductor wire to connect the two, if you're looking for a small desktop unit.

(OR get a 51x rack)

 

[Enchilada]

Sounds like good advice to me...

The main reason I ask is because I am in Australia and I'm building a preamp for a mate in the USA. I don't want to have to buy a step down transformer to test it so wall wart appeared to be the logical choice.

 

[gemini86]

If you buy a transformer with dual primaries, you can wire in a 120/240 switch. A wal wart is only logical when you can do the power conversion inside easily. For companies that are cranking out large numbers on mass-produced PCBs using robots to place all the components, that's no problem. But it's a much larger undertaking designing a one-off milti-output switching supply into a small space using prototyping gear.

 

[Enchilada]

I've not seen any transformers with dual primaries. I've been looking at au.element14.com (formerly Farnell). Could you please post a link to one so I understand what I'm looking for?

Thanks,

Kris

 

[chrispbass]

I've not seen any transformers with dual primaries. I've been looking at au.element14.com (formerly Farnell). Could you please post a link to one so I understand what I'm looking for?

Thanks,

Kris

http://www.rapidonline.com/pdf/88-3781.pdf

scroll down to page 3, you can see the dual primary and secondary windings.

for 230v, you would link grey and violet together (insulated connection) and use brown and blue as your live and neutral.

for 115v you would link blue and violet (use this as your 'neutral') and grey and brown (use this as your 'live').

as mentioned, you can get a selector switch which does this for you without having to open up the unit and rewire.

hope that helps...

Chris

 

[Enchilada]

Can I do the same with one of these? http://au.element14.com/multicomp/mcta015-15/transformer-15va-2-x-15v/dp/9530266

The datasheet tells me that primary is 115 or 230 although the description on the above link only lists 115V.